Carriers and Return Cases in Scarlet Fever

1. In view of the high carrier rate on discharge from hospital, the bacteriological examination of swabs from scarlet fever patients is of no value in the detection of probable infecting cases.2. There is, however, a definite relationship between the degree of infection, as measured by the profusion of haemolytic streptococci in cultures on discharge, and the likelihood of the patient infecting others.3. The causal connection between “infecting” case and return case is strongly supported by finding the same serological type ofStreptococcus pyogenesin both cases.4. A patient who has had complications in hospital is slightly more liable to become an infecting case than one whose course has been uncomplicated.5. The commonest age group of infecting cases is 5–10 years.6. The majority (70 per cent.) of the return cases occurred within 14 days of the arrival home of the infecting case.7. Overcrowding in the home, and the number of the susceptibles exposed do not appear to be important factors in the production of return cases.8. A history of tonsillectomy does not appear to bear any important relationship to the occurrence of infecting cases, but the inconclusive nature of our findings indicates the desirability of further investigation of this question and that of the relation of the condition of the tonsils to their infectivity.9. Discharge from hospital as early as is consistent with a satisfactory clinical condition is shown to be advantageous from the point of view both of the patient and of the hospital administration.10. The administration of scarlatinal antitoxin is likely to render a patient less liable to convey infection on discharge.